Field of the Invention
The invention relates to a voltage regulation circuit, and more particularly to a voltage regulation circuit for regulating a supply voltage provided by an automotive battery of an automobile.
Description of the Related Art
In a conventional power supply device of an automobile, a supply voltage provided by an automotive battery is regulated by a regulation circuit in response to the operation state of the automobile. A feedback voltage related to the supply voltage is provided to a set of voltage division resistors for a regulation operation of the supply voltage. The set of voltage division is disposed outside of the chip of the regulation circuit. By changing or programming the resistance ratio of the voltage division resistors, the level of the supply voltage can be regulated. In the conventional power supply device, a chip requires additional pins to charge or program a resistance ratio. Moreover, it is necessary to ensure switches which are used to change or program the resistance ratio large enough for the high accuracy of the resistance ratio. The large switch implies large area, and large production cost as well.